Chennai vs metropolis

Chennai and metropolis both are nouns.

Word	Noun	Adjective	Verb	Adverb
Chennai	Yes	No	No	No
metropolis	Yes	No	No	No

Chennai (noun)	metropolis (noun)
a city in Tamil Nadu on the Bay of Bengal; formerly Madras	people living in a large densely populated municipality
	a large and densely populated urban area; may include several independent administrative districts